Control of metal–support interaction for tunable CO hydrogenation performance over Ru/TiO2 nanocatalysts

Abstract

The catalytic behavior of CO hydrogenation can be modulated by metal–support interactions, while the role of the support remains elusive. Herein, we demonstrate that the presence of strong metal–support interactions (SMSI) depends strongly on the crystal phase of TiO₂ (rutile or anatase) and the treatment conditions for the TiO₂ support, which could critically control the activity and selectivity of Ru-based nanocatalysts for CO hydrogenation. High CO conversion and olefin selectivity were observed for Ru/rutile-TiO₂ (Ru/r-TiO₂), while catalysts supported by anatase (a-TiO₂) showed almost no activity. Characterization confirmed that the SMSI effect could be neglected for Ru/r-TiO₂, while it is dominant on Ru/a-TiO₂ after reduction at 300 °C, resulting in the coverage of Ru nanoparticles by TiO_x overlayers. Such SMSI could be suppressed by H₂ treatment of the a-TiO₂ support and the catalytic activity of the as-obtained Ru/a-TiO₂(H₂) can be greatly elevated from almost inactive to >50% CO conversion with >60% olefin selectivity. Further results indicated that the surface reducibility of the TiO₂ support determines the SMSI state and catalytic performance of Ru/TiO₂ in the CO hydrogenation reaction. This work offers an effective strategy to design efficient catalysts for the FTO reaction by regulating the crystal phase of the support.